Aluminum oxide-forming composition and method for producing same, and polyolefin-based polymer nanocomposite containing zinc oxide particles or aluminum oxide particles and method of producing same

ABSTRACT

A method for producing aluminum oxide is provided. The method uses an aluminum-oxide-forming agent containing a partially hydrolyzed aluminum alkyl compound containing an aluminum trialkyl or a mixture thereof, and a solvent. It is thus possible to produce an aluminum oxide thin film or aluminum oxide particles on or in a substrate that is not resistant to polar solvents. A method of producing a polyolefin-based polymer nanocomposite containing zinc oxide particles or aluminum oxide particles using a solution containing a partially hydrolyzed zinc alkyl or a solution containing a partially hydrolyzed aluminum alkyl is also provided. The polyolefin-based polymer nanocomposite contains a polyolefin substrate and zinc oxide particles or aluminum oxide particles, and does not contain a dispersant. The zinc oxide particles or aluminum oxide particles have an average particle size of less than 100 nm.

TECHNICAL FIELD

The present invention relates to a composition for forming aluminumoxide, which comprises a solution containing an alkyl aluminum partialhydrolyzate, a method for producing same, and a method for producingaluminum oxide. By using the solution containing an alkyl aluminumpartial hydrolyzate of the present invention, it is possible to form analuminum oxide thin film on a substrate that is not resistant to polarsolvents or to incorporate aluminum oxide particles in a substrate thatis not resistant to polar solvents. The present invention also relatesto a polyolefin-based polymer nanocomposite containing zinc oxideparticles or aluminum oxide particles and a method for producing same.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority of Japanese Patent ApplicationNo. 2016-98174, which was filed on 16 May 2016, and Japanese PatentApplication No. 2016-215555, which was filed on 02 November 2016, andall the statements in those applications are hereby incorporated byreference.

BACKGROUND ART

(First Aspect of Invention)

Aluminum oxide exhibits excellent characteristics in terms of highstrength, high heat resistance, high thermal conductivity, lowcoefficient of thermal expansion, insulation properties, and the like,and is therefore widely used in a variety of applications.

Aluminum oxide thin films are used in applications such as producingaluminum oxide sheets for electronic materials and aluminum oxide films,producing catalyst carriers, imparting heat resistance, impartingbarrier properties against air and moisture, imparting ananti-reflection effect, an anti-static effect, an anti-fogging effect,abrasion resistance and the like, and as binders for producing ceramics.Such aluminum oxide thin films require high purity (see NPL 1).Specifically, examples of applications of such aluminum oxide thin filmsinclude protective films for cutting tools, insulating films forsemiconductors, magnetic bodies, solar cells and the like, packagingmaterials for surface devices, magnetic heads, infrared radiationsensors, foods, medicines, medical equipment and the like, opticalmembers, and the like.

Aluminum oxide particles are used in applications such as ceramic rawmaterials, fillers for rubbers and plastics, and abrasive materials (seeNPL 2). Specifically, examples of applications of aluminum oxideparticles include fillers for resins for high heat conduction, fillersfor adjusting the refractive index, reflectance, workability,flexibility and the like of resins, and sintering raw materials for fineceramics.

Aluminum oxide thin films are formed using methods such as sputteringmethods, chemical vapor deposition (CVD) methods and atomic layerdeposition (ALD) methods.

However, because methods such as sputtering methods, CVD methods and ALDmethods require the use of large sealed containers, problems occur suchas production costs for aluminum oxide thin films increasing andmaterial usage efficiency decreasing.

Coating methods such as spin coating methods, dip coating methods,screen printing methods, die coating methods and spray coating methodsdo not require use of sealed containers, unlike the methods mentionedabove, and have advantages such as involving simple apparatuses,enabling rapid film production speeds and enabling aluminum oxide thinfilms to be produced with lower production costs.

A variety of investigations have been carried out into formation ofaluminum oxide thin films using coating methods (see PTL 1 to 4).

In the method disclosed in PTL 1, however, in cases where a passivationfilm is produced by a heat treatment (firing), it is necessary todegrease (remove) residual organic components such as binder resins andligands by firing. As a result, there was the problem that a long firingtime was required or a heat treatment at a high temperature ofapproximately 400° C. to 1000° C. was required.

Furthermore, there is the problem that transparent aluminum oxide(having a transmittance of 80% or more of visible light having awavelength of 550 nm) is difficult to obtain by means of heat treatmentat a low temperature. In cases where transparent aluminum oxide was tobe obtained, there was the problem that non-heat resistant substrates,such as plastics, could not be used because firing at temperatures of300° C. or higher was necessary.

In the method disclosed in PTL 2, because additives and solvents arecarboxylic acids and polar solvents such as ethers, there was theproblem that it was not possible to use substrates such as acrylicresins and polycarbonate resins, which are not resistant to polarsolvents.

PTL 3 and 4 disclose methods for forming alumina thin films andcompositions for forming alumina thin films. These documents disclosemethylaluminoxane or the like as an aluminum-containing compoundcontained in a composition for forming an alumina thin film. There areno production examples of aluminum oxide thin films using this, anddescriptions of composition solutions are abstract.

Furthermore, PTL 3 and 4 disclose examples in which thin films areproduced using a dibutyl aluminum hydride solution, a tri-n-octylaluminum solution or a tri-n-dodecyl aluminum solution. However,problems occurred, such as aluminum usage efficiency greatlydeteriorating, and especially reproducibility in terms of film qualitybeing difficult to achieve when producing a film in air, due to dibutylaluminum hydride, tri-n-octyl aluminum and tri-n-dodecyl aluminumvaporizing with a solvent when the solvent was removed by drying.

(Second Aspect of Invention)

A polymer-based nanocomposite is a composite material in which aninorganic oxide is dispersed in a polymer, generally in the form ofultrafine particles having sizes of 1 to 100 nm. Unlike conventionalinorganic oxide filler-filled polymers, a polymer-based nanocompositehas the characteristics of the added quantity of an inorganic oxidebeing low and the surface area of the inorganic oxide being greatlyincreased.

Because the distance between inorganic oxide particles is extremelysmall in a polymer-based nanocomposite as a result of thecharacteristics mentioned above, interactions between the inorganicoxide and the polymer matrix are greatly increased and thecharacteristics of the polymer substrate are improved, and it can beexpected that the polymer is imparted with functionality (see NPL 3).

It is known that a polymer-based nanocomposite that contains zinc oxideexhibits improved polymer substrate characteristics, such as improvedthermal stability of the polymer matrix, improved abrasion resistance,increased refractive index, and improved stability to ultravioletradiation.

In addition, it is known that a polymer-based nanocomposite thatcontains zinc oxide imparts functionality such as electricalconductivity, ultraviolet radiation absorption, antibacterial propertiesand refractive index adjustment (see PTL 5).

It is expected that polymer-based nanocomposites containing aluminumoxide particles will also impart functionality such as thermalconductivity, abrasion resistance and refractive index adjustment (seePTL 6).

Even in conventional inorganic oxide filler-filled polymers,investigations have been carried out by forming polymers that containmicron sized aluminum oxide, aluminum nitride, or the like, havingaverage particle diameters of 55 μm as fillers to impart thermalconductivity (see PTL 7).

Meanwhile, among polymers, polyolefins are commonly used plastics whichare inexpensive, have high melting points, exhibit molding processingproperties and exhibit excellent recycling properties. In recent years,many investigations have been carried out into replacing inorganicmaterials and engineering plastics with polyolefin-based nanocompositesobtained by nanocompositing polyolefins and inorganic oxides.

However, dispersing inorganic oxides in polyolefins that exhibit poorpolarity is not easy, and addition of dispersing agents, chemicalmodification of inorganic oxide surfaces, and the like, has been carriedout in order to improve dispersibility. However, problems such as lossof improvement effects exhibited by other additives occurred as a resultof interactions between dispersing agents and chemical modificationagents and other additives such as flame retardants, antidegradants andcoloring agents contained in industrial use polyolefins.

Furthermore, in the production method disclosed in PTL 5, a thiolcompound or a dispersing agent such as a silane coupling agent must beadded in order to prevent aggregation of the inorganic oxide. Problemsoccurred, such as unpleasant odors being generated as a result of use ofa thiol compound, increased costs caused by use of a silane couplingagent, and loss of improvement effects exhibited by other additives as aresult of interactions between the dispersing agent and other additives.

Many investigations have been carried out into inorganic oxidefiller-filled polymers, such as that disclosed in PTL 7, rather thannanocomposites. In such cases, problems occurred, such as the need toadd a dispersing agent, as mentioned above, interactions between thepolymer and the inorganic oxide being weak in comparison withnanocomposites, the need to use a large quantity of inorganic oxidefiller, and the characteristics of the polymer being greatly reduced.

Furthermore, polyolefins have been mentioned as the polymers in thepolymer-based nanocomposite and inorganic oxide filler-filled polymerdisclosed in PTL 5 and 7. However, there are no specific examples ofmethods for producing these, and it is surmised that the inorganic oxidewill actually aggregate in cases where a polyolefin that exhibits poorpolarity is used.

The production method disclosed in PTL 6 can produce a polyolefin-basednanocomposite containing aluminum oxide without using a dispersingagent, but significant improvements in inorganic oxide dispersion areneeded.

-   [PTL 1] Japanese Examined Patent Publication No. S61-050903-   [PTL 2] Japanese Patent No. 5332743-   [PTL 3] WO 2012/053433-   [PTL 4] WO 2012/053436-   [PTL 5] Japanese Translation of PCT Application No. 2009-510180-   [PTL 6] Japanese Patent Application Publication No. 2016-124942-   [PTL 7] Japanese Patent Application Publication No. 2015-117260-   [NPL 1] Yasaka, JETI., 10 (2005) pages 134 to 140-   [NPL 2] Uchida et al, Sumitomo Chemical Company, Limited, technical    journal, 1 (2000), pages 45 to 49-   [NPL 3] Kiyoshi NAKAJO, “Technical Trends in Polymer-based    Nanocomposites”, CMC Publishing, page 3, 2001

All the statements in PTL 1 to 7 and NPL 1 to 3 are hereby incorporatedby reference.

SUMMARY OF INVENTION Technical Problem

In cases where the methods or materials disclosed in PTL 1 to 4 areused, it is not possible to form an aluminum oxide thin film on asubstrate that is not resistant to polar solvents or form aluminum oxideparticles in a substrate that is not resistant to polar solvents.

As a result, the purpose of the first aspect of the present invention isto provide an agent that can form an aluminum oxide thin film on asubstrate such as an acrylic resin or polycarbonate resin that is notresistant to polar solvents such as ethers, alcohols, ketones,carboxylic acids and esters, or can form aluminum oxide particles insuch a substrate.

The purpose of the second aspect of the present invention is to provide,without adding a dispersing agent, a polyolefin-based nanocompositewhich contains zinc oxide particles or aluminum oxide particles in awell dispersed state in a polyolefin base material and which containszinc oxide particles or aluminum oxide particles having an averageparticle diameter of less than 100 nm even if the oxide concentration is3 wt % or more, and a method for producing same.

Solution to Problem

The first aspect of the present invention is as follows.

-   [1]

A method for producing a composition for forming a particulate or thinfilm-shaped aluminum oxide, which is comprised of a solution containingan alkyl aluminum partial hydrolyzate, the method comprising: addingwater to a solution containing an alkyl aluminum compound and anon-polar organic solvent at a molar ratio of 0.5 to 1.4 relative toaluminum in the alkyl aluminum compound to produce the solutioncontaining the alkyl aluminum partial hydrolyzate, wherein the alkylaluminum compound is comprised of a trialkyl aluminum or a mixturethereof, wherein the alkyl groups may be the same or different and have4 to 12 carbon atoms.

-   [2]

The production method according to [1], wherein the trialkyl aluminum isan alkyl aluminum compound represented by general formula (1) below.

[C1]

AlR¹ ₃   (1)

in the formula, R¹ represents an isobutyl group, an n-hexyl group or ann-octyl group, and the three R¹ groups may be the same or different.)

-   [3]

The production method according to [2], wherein the trialkyl aluminum istriisobutyl aluminum.

-   [4]

The production method according to any one of [1] to [3], wherein thenon-polar organic solvent is an aromatic hydrocarbon.

-   [5]

The production method according to [4], wherein the aromatic hydrocarbonis toluene and/or xylene.

-   [6]

The production method according to any one of [1] to [3], wherein thenon-polar organic solvent is an aliphatic hydrocarbon.

-   [7]

The production method according to [6], wherein the aliphatichydrocarbon is at least one aliphatic hydrocarbon selected from thegroup consisting of heptane, methylcyclohexane, ethylcyclohexane,n-decane, n-undecane, n-dodecane and tridecane.

-   [8]

A composition for forming a particulate or thin film-shaped aluminumoxide, which is comprised of a solution containing an alkyl aluminumpartial hydrolyzate and a non-polar organic solvent, wherein the alkylgroups in the alkyl aluminum partial hydrolyzate may be the same ordifferent and have 4 to 12 carbon atoms, the molar ratio of alkyl groupsrelative to aluminum atoms falls within the range of 0.2 to 2, and themolar ratio of oxygen atoms relative to aluminum atoms falls within therange of 1.4 to 0.5.

-   [9]

The composition according to [8], wherein the alkyl groups are at leastone alkyl group selected from the group consisting of isobutyl groups,n-hexyl groups and n-octyl groups.

-   [10]

The composition according to [8] or [9], wherein the non-polar organicsolvent is an aromatic hydrocarbon.

-   [11]

The composition according to [10], wherein the aromatic hydrocarbon istoluene and/or xylene.

-   [12]

The composition according to [8] or [9], wherein the non-polar organicsolvent is an aliphatic hydrocarbon.

-   [13]

The composition according to [12], wherein the aliphatic hydrocarbon isat least one aliphatic hydrocarbon selected from the group consisting ofheptane, methylcyclohexane, ethylcyclohexane, n-decane, n-undecane,n-dodecane and tridecane.

-   [14]

A method for producing an aluminum oxide thin film, the methodcomprising: coating a substrate with the composition according to anyone of [8] to [13], and then removing the non-polar organic solvent toform an aluminum oxide thin film.

-   [15]

A method for producing a particulate aluminum oxide-containingsubstrate, the method comprising: mixing the composition according toany one of [8] to [13] with a substrate-forming binder, and thenremoving the non-polar organic solvent to form a particulate aluminumoxide in the binder.

The second aspect of the present invention is as follows.

-   [16]

A method for producing a polyolefin-based polymer nanocompositecontaining zinc oxide particles, the method being characterized by usinga solution containing a partial hydrolyzate of a dialkyl zinc, whereinthe alkyl groups may be the same or different and have 1 to 14 carbonatoms, and a polyolefin powder.

-   [17]

The production method according to [16], which comprises (A) a step ofimpregnating a polyolefin powder with a solution containing a partialhydrolyzate of a dialkyl zinc (here, the alkyl groups may be the same ordifferent and have 1 to 12 carbon atoms),

(B) a step of removing an organic solvent contained in the polyolefinpowder, and

(D) a step of melting the polyolefin powder by heating to obtain apolyolefin-based polymer nanocomposite containing zinc oxide particles.

-   [18]

The production method according to [17], which comprises, between steps(B) and (D),

(C) a step of supplying moisture to the alkyl zinc partial hydrolyzatecontained in the polyolefin powder to facilitate hydrolysis of thepartial hydrolyzate.

-   [19]

The production method according to any one of [16] to [18], wherein thesolution containing a partial hydrolyzate is prepared by adding water ata molar ratio of 0.5 to 1.4 relative to zinc in a dialkyl zinc to asolution containing the dialkyl zinc and an organic solvent.

-   [20]

The production method according to any one of [16] to [19], wherein themolar ratio of water relative to zinc in the dialkyl zinc falls withinthe range of 0.5 to 0.9.

-   [21]

The production method according to any one of [16] to [20], wherein thedialkyl zinc is represented by general formula (2-1) below.

[C2]

ZnR¹⁰ ₂   (2-1)

In the formula, R¹⁰ represents a methyl group, an ethyl group, ann-butyl group, an isobutyl group, a sec-butyl group or a tert-butylgroup, and the two R¹⁰ groups may be the same or different.

-   [22]

The production method according to any one of [16] to [21], wherein thedialkyl zinc is diethyl zinc.

-   [23]

The production method according to any one of [16] to [22], wherein thepolyolefin powder is a polyethylene powder or a polypropylene powder.

-   [24]

The production method according to any one of [16] to [23], wherein thepolyolefin powder has been prepared using a Ziegler-Natta catalyst.

-   [25]

A polyolefin-based polymer nanocomposite, which comprises a polyolefinbase material and zinc oxide particles and does not contain a dispersingagent, wherein the average particle diameter of the zinc oxide particlesis less than 100 nm.

-   [26]

The nanocomposite according to [25], wherein the content of the zincoxide particles is 3 wt % or more.

-   [27]

The nanocomposite according to [25] or [26], wherein the zinc oxideparticles are dispersed in the polyolefin base material.

-   [28]

A method for producing a polyolefin-based polymer nanocomposite whichcontains aluminum oxide particles, the method being characterized byusing a solution containing a partial hydrolyzate of an alkyl aluminumcompound comprised of a trialkyl aluminum or a mixture thereof, and apolyolefin powder.

-   [29]

The production method according to [28], which comprises (E) a step ofimpregnating a polyolefin powder with a solution containing a partialhydrolyzate of an alkyl aluminum compound comprised of a trialkylaluminum or a mixture thereof wherein the alkyl groups may be the sameor different and have 1 to 12 carbon atoms,

(F) a step of drying the polyolefin powder by removing an organicsolvent contained therein, and

(H) a step of melting the polyolefin powder by heating to obtain apolyolefin-based polymer nanocomposite containing aluminum oxideparticles.

-   [30]

The production method according to [29], which comprises, between steps(F) and (H),

(G) a step of supplying moisture to the alkyl aluminum partialhydrolyzate contained in the polyolefin powder to facilitate hydrolysisof the partial hydrolyzate.

-   [31]

The production method according to any one of [28] to [30], wherein thesolution containing a partial hydrolyzate is prepared by adding water toa solution containing an organic solvent and an alkyl aluminum compoundcomprised of a trialkyl aluminum or a mixture thereof at a molar ratioof 0.5 to 1.4 relative to aluminum in the alkyl aluminum compound.

-   [32]

The production method according to any one of [28] to [31], wherein thetrialkyl aluminum is an alkyl aluminum compound represented by generalformula (2-2) below.

[C3]

AlR² ₃   (2-2)

In the formula, R² represents a methyl group, an ethyl group, anisobutyl group, an n-hexyl group or an n-octyl group, and the three R²groups may be the same or different.

-   [33]

The production method according to any one of [28] to [32], wherein thetrialkyl aluminum is triethyl aluminum.

-   [34]

The production method according to any one of [28] to [33], wherein thetrialkyl aluminum is triisobutyl aluminum.

-   [35]

The production method according to any one of [28] to [34], wherein thepolyolefin powder is a polyethylene powder or a polypropylene powder.

-   [36]

The production method according to any one of [28] to [35], wherein thepolyolefin powder has been prepared using a Ziegler-Natta catalyst.

-   [37]

A polyolefin-based polymer nanocomposite, which contains a polyolefinbase material and aluminum oxide particles and does not contain adispersing agent, wherein the average particle diameter of the aluminumoxide particles is less than 100 nm.

-   [38]

The nanocomposite according to [37], wherein the content of the aluminumoxide particles is 3 wt % or more.

-   [39]

The nanocomposite according to [37] or [38], wherein the aluminum oxideparticles are dispersed in the polyolefin base material.

-   [40]

The nanocomposite according to any one of [37] to [39], which furthercontains aluminum hydroxide particles.

Advantageous Effects of Invention

According to the first aspect of the present invention, by using analkyl aluminum partial hydrolyzate composition solution that does notcontain a polar solvent, it is possible to form an aluminum oxide thinfilm on a substrate that is not resistant to polar solvents or formaluminum oxide particles in a substrate that is not resistant to polarsolvents.

According to the second aspect of the present invention, it is possibleto provide a polyolefin-based nanocomposite which does not contain adispersing agent and which contains zinc oxide particles or aluminumoxide particles having an average particle diameter of less than 100 nmin a polyolefin base material. Furthermore, the nanocomposite of thepresent invention contains zinc oxide particles or aluminum oxideparticles in a well dispersed state in the nanocomposite even if thecontent of the zinc oxide particles or aluminum oxide particles is 3 wt% or more.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a transmission IR spectrum of a product obtained by drying atoluene solution of a triisobutyl aluminum hydrolyzate composition.

FIG. 2 is a transmission IR spectrum of a product obtained by drying atoluene solution of a tri-n-octyl aluminum hydrolyzate composition.

FIG. 3 is a transmission IR spectrum of a product obtained by drying adecane solution of a triisobutyl aluminum hydrolyzate composition.

FIG. 4 is a transmission IR spectrum of a product obtained by drying adecane solution of a tri-n-octyl aluminum hydrolyzate composition.

FIG. 5 is a photograph showing the appearance of the aluminum oxide thinfilm according to Synthesis Example 1-1.

FIG. 6 is an ATR IR spectrum of the aluminum oxide thin film accordingto Synthesis Example 1-1.

FIG. 7 is an ATR IR spectrum of a glass substrate (Eagle XG availablefrom Corning Incorporated).

FIG. 8 is a photograph showing the appearance of an aluminum oxide thinfilm that uses Synthesis Example 1-1.

FIG. 9 is an ATR IR spectrum of an aluminum oxide thin film that usesSynthesis Example 1-1.

FIG. 10 is a photograph showing the appearance of an aluminum oxide thinfilm that uses Synthesis Example 1-1.

FIG. 11 is an ATR IR spectrum of an aluminum oxide thin film that usesSynthesis Example 1-1.

FIG. 12 is an ATR IR spectrum of an acrylic resin substrate (ACRYLITE EXavailable from Mitsubishi Rayon Co., Ltd.).

FIG. 13 is a photograph showing the appearance of an aluminum oxide thinfilm that uses Synthesis Example 1-4.

FIG. 14 is an ATR IR spectrum of an aluminum oxide thin film that usesSynthesis Example 1-4.

FIG. 15 is a photograph showing the appearance of an aluminum oxide thinfilm that uses Synthesis Example 1-4.

FIG. 16 is an ATR IR spectrum of an aluminum oxide thin film that usesSynthesis Example 1-4.

FIG. 17 is a photograph showing the appearance of an aluminum oxide thinfilm that uses Synthesis Example 1-5.

FIG. 18 is an ATR IR spectrum of an aluminum oxide thin film that usesSynthesis Example 1-5.

FIG. 19 is a FT-IR spectrum of a polypropylene nanocomposite produced inExample 2-1, which contains 5 wt % of zinc oxide (the top spectrum is aspectrum of a propylene homopolymer powder only, and the second spectrumis a spectrum of Example 2-1).

FIG. 20 is a TEM image of a polypropylene nanocomposite produced inExample 2-1, which contains 5 wt % of zinc oxide.

FIG. 21 is a powder X-Ray diffraction spectrum of a polypropylenenanocomposite produced in Example 2-1, which contains 5 wt % of zincoxide.

FIG. 22 is a FT-IR spectrum of a polypropylene nanocomposite produced inExample 2-2, which contains 5 wt % of steam-treated zinc oxide (the topspectrum is a spectrum of a propylene homopolymer powder only, and thesecond spectrum is a spectrum of Example 2-2).

FIG. 23 is a TEM image of a nanocomposite produced in Example 2-2, whichcontains 5 wt % of steam-treated zinc oxide.

FIG. 24 is a powder X-Ray diffraction spectrum of a nanocompositeproduced in Example 2-2, which contains 5 wt % of steam-treated zincoxide.

FIG. 25 is a FT-IR spectrum of a polypropylene nanocomposite produced inExample 2-3, which contains 5 wt % of aluminum oxide (the top spectrumis a spectrum of a propylene homopolymer powder only, and the secondspectrum is a spectrum of Example 2-3).

FIG. 26 is a TEM image of a polypropylene nanocomposite produced inExample 2-3, which contains 5 wt % of aluminum oxide.

FIG. 27 is a FT-IR spectrum of a nanocomposite produced in Example 2-4,which contains 5 wt % of steam-treated aluminum oxide (the top spectrumis a spectrum of a propylene homopolymer powder only, and the bottomspectrum is a spectrum of Example 2-4).

FIG. 28 is a TEM image of a nanocomposite produced in Example 2-4, whichcontains 5 wt % of steam-treated aluminum oxide.

DESCRIPTION OF EMBODIMENTS

[Method for producing solution containing alkyl aluminum partialhydrolyzate (first aspect)]

The present invention relates to a method for producing a compositionfor forming a particulate or thin film-shaped aluminum oxide, which iscomprised of a solution containing an alkyl aluminum partialhydrolyzate, the method including a step of adding water at a molarratio of 0.5 to 1.4 relative to aluminum in an alkyl aluminum compoundto a solution containing a partial hydrolyzate of the alkyl aluminumcompound, which is comprised of a trialkyl aluminum or a mixture thereofwherein the alkyl groups may be the same or different and have 4 to 12carbon atoms, and a non-polar organic solvent to obtain the solutioncontaining an alkyl aluminum partial hydrolyzate.

The trialkyl aluminum is preferably an alkyl aluminum compoundrepresented by general formula (1) below.

[C4]

AlR¹3 (1)

In the formula, R¹ represents an isobutyl group, an n-hexyl group or ann-octyl group, and the three R¹ groups may be the same or different.

Examples of the compound represented by general formula (1) includetriisobutyl aluminum, tri-n-hexyl aluminum, tri-n-octyl aluminum,tridodecyl aluminum and tritetradecyl aluminum. From the perspective ofbeing inexpensive in terms of cost per unit mass of aluminum and theperspectives of the aluminum concentration in a solution prepared fromthe compound and the aluminum oxide conversion concentration,triisobutyl aluminum, tri-n-hexyl aluminum and tri-n-octyl aluminum arepreferred, and triisobutyl aluminum is particularly preferred.

As examples of the compound represented by general formula (1),trimethyl aluminum and triethyl aluminum are not preferred from theperspectives of difficulty in controlling reactivity with water withoutpolar solvents and costs being incurred due to the need for specialistequipment for adding water, and trimethyl aluminum in particular is notpreferred due to being expensive in terms of cost per unit mass ofaluminum.

Examples of these non-polar solvents include aromatic hydrocarbons andaliphatic hydrocarbons.

Examples of aromatic hydrocarbons include benzene, toluene, o-xylene,m-xylene, p-xylene, mixed xylene (xylene), ethylbenzene,isopropylbenzene, mesitylene, pseudocumene, amylbenzene, o-cymene,m-cymene, p-cymene, mixed cymene (cymene), o-diethylbenzene,m-diethylbenzene, p-diethylbenzene, mixed diethylbenzene(diethylbenzene), cyclohexylbenzene and tetralin.

From the perspective of being inexpensive and the perspective that asuitably high boiling point is preferred in order to increase filmformation properties, toluene and xylene are particularly preferred.

Examples of aliphatic hydrocarbons include pentane, methylcyclopentane,hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, heptane,nonane, octane, n-decane, n-undecane, n-dodecane, tridecane,tetradecane, kerosene, decalin, petroleum ether, petroleum benzine,solvent naphtha, dipentene, turpentine oil, o-menthane, m-menthane,p-menthane, mixed menthane (menthane) and ligroin.

From the perspective of being inexpensive and the perspective that asuitably high boiling point is preferred in order to increase filmformation properties, heptane, methylcyclohexane, ethylcyclohexane,n-decane, n-undecane, n-dodecane and tridecane are particularlypreferred.

The non-polar solvents cited here are the aromatic hydrocarbons andaliphatic hydrocarbons mentioned above, and polar solvents areether-based solvents such as diethyl ether, dipropyl ether, diisopropylether, dibutyl ether, tetrahydrofuran, dioxane, anisole andmethyl-t-butyl ether; alcohol-based solvents such as ethanol, isopropylalcohol, butanol, ethylene glycol, diethylene glycol, ethylene glycolmonomethyl ether, ethylene glycol monobutyl ether, ethylene glycolmonoacetate, ethylene glycol dibutyl ether, propylene glycol,dipropylene glycol, dipropylene glycol monomethyl ether and hexyleneglycol; ketone- and aldehyde-based solvents such as acetone,acetophenone, cyclohexanone, diacetone alcohol, methyl isobutyl ketoneand methyl ethyl ketone; carboxylic acids such as acetic acid and formicacid; ester-based solvents such as ethyl acetate, n-butyl acetate,s-butyl acetate and y-butyl lactone; nitrogen-containing compound-basedsolvents such as acetonitrile, propionitrile, butyronitrile andtriethylamine; and ethylene carbonate and propylene carbonate.

Here, polarity is evaluated in terms of dielectric constant, dipolemoment, solubility parameter, or the like, and solvents areexperimentally classified into non-polar solvents and polar solvents, asshown above.

The alkyl aluminum compound is partially hydrolyzed using water at amolar ratio within the range of 0.5 to 1.4 relative to the alkylaluminum compound. If the molar ratio of water relative to the alkylaluminum compound is less than 0.5, a liquid form tends to remain evenafter the solvent is removed by drying and it is difficult to form auniform aluminum oxide thin film or particles. From the perspective offorming a uniform aluminum oxide thin film or particles, the molar ratioof water relative to the alkyl aluminum compound is preferably 0.5 ormore, and more preferably 0.8 or more. Meanwhile, if the molar ratio ofwater relative to the alkyl aluminum compound exceeds 1.4, insoluble gelor solid precipitates in the solvent and it is difficult to form auniform aluminum oxide thin film or particles due to the presence of thegel or solid, and this molar ratio is therefore preferably 1.4 or less,and more preferably 1.3 or less. Precipitated gel or solid can beremoved by means of decanting, filtration or the like.

The partial hydrolysis reaction of the alkyl aluminum compound iscarried out by adding water to the non-polar solvent in an inert gasatmosphere.

The concentration of the alkyl aluminum compound in the alkyl aluminumcompound solution to which the water is added can be 2 to 98 mass %.

The period of addition of the water to the alkyl aluminum compoundsolution can be specified as appropriate according to the types,volumes, and the like, of the raw materials being mixed, but can fallwithin the range of 1 minute to 10 hours. The temperature during theaddition can be selected as appropriate within the range of −15° C. to150° C. However, this temperature preferably falls within the range of−15° C. to 80° C. in view of safety and the like.

Following addition of water or a water-containing solution, an agingreaction can be carried out fora period of 0.1 to 50 hours in order forthe partial hydrolysis reaction between the alkyl aluminum compound andwater to progress further. The temperature during the aging reaction canbe selected as appropriate within the range of −15° C. to 150° C.However, this temperature preferably falls within the range of 25° C. to150° C. from perspectives such as shortening the aging reaction time.

The alkyl aluminum compound, water and non-polar solvent can beintroduced into a reaction vessel using any commonly used method. Thepressure inside the reaction vessel is not limited. The hydrolysisreaction step is not particularly limited, and can be a batch typeprocess, a semi-batch type process or a continuous process, but a batchtype process is preferred.

A solution containing the alkyl aluminum partial hydrolyzate is obtainedby means of this partial hydrolysis reaction. Partial hydrolyzatecompositions have long been analyzed in cases where an alkyl aluminumcompound is triisobutyl aluminum, but compositional analysis results ofproducts vary from report to report, and product compositions have notbeen clearly specified. In addition, the product composition variesaccording to differences in the solvent, the concentration, the addedmolar ratio of water, the addition temperature, the reactiontemperature, the reaction period, and the like.

[Aluminum oxide-forming composition]

The present invention relates to an aluminum oxide-forming composition,and this composition is a composition for forming particulate or thinfilm-shaped aluminum oxide, which comprises a solution containing analkyl aluminum partial hydrolyzate and a non-polar organic solvent,wherein the alkyl groups in the alkyl aluminum partial hydrolyzate maybe the same or different and have 4 to 12 carbon atoms, the molar ratioof alkyl groups relative to aluminum atoms falls within the range of 0.2to 2, and the molar ratio of oxygen atoms relative to aluminum atomsfalls within the range of 1.4 to 0.5. The alkyl groups preferably have 4to 8 carbon atoms, and are more preferably isobutyl groups, n-hexylgroups or n-octyl groups.

The inventors of the present invention found that an alkyl aluminumpartial hydrolyzate in which each of the alkyl groups has 4 to 12 carbonatoms, the molar ratio of alkyl groups relative to aluminum atoms fallswithin the range of 0.2 to 2, and the molar ratio of oxygen atomsrelative to aluminum atoms falls within the range of 1.4 to 0.5 can bedissolved even in non-polar organic solvents.

From the perspective of being able to be dissolved well in non-polarorganic solvents, and especially the aromatic hydrocarbons and aliphatichydrocarbons mentioned above, the molar ratio of alkyl groups relativeto aluminum atoms preferably falls within the range of 0.2 to 2, morepreferably falls within the range 0.8 to 1.8, and further preferablyfalls within the range of 1.0 to 1.5. The molar ratio of oxygen atomsrelative to aluminum atoms preferably falls within the range of 1.4 to0.5, more preferably falls within the range of 1.4 to 0.7, and furtherpreferably falls within the range of 1.3 to 0.9.

It is presumed that the alkyl aluminum partial hydrolyzate in the methodof the present invention is a mixture of compounds including structuralunits represented by general formula (2) below.

In the formula, R¹ is defined in the same way as R¹ in general formula(1), and m is an integer between 1 and 80.

In cases where solids and the like are precipitated following completionof the partial hydrolysis reaction, the solids and the like can beremoved through purification by means of a method such as filtration.

The solid content concentration in the solution containing the alkylaluminum partial hydrolyzate can be adjusted by means of concentrating(solvent removal). In addition, the solid content concentration,polarity, viscosity, boiling point, profitability, and the like, can beadjusted as appropriate by adding the solvent used in the reaction or anon-polar solvent that is different from that used in the reaction.

Examples of polar solvents that are different from the solvent used inthe reaction include the same solvents as the non-polar solventsmentioned above.

The content of the alkyl aluminum partial hydrolyzate in the solutioncontaining the alkyl aluminum partial hydrolyzate of the presentinvention can be decided as appropriate according to the intended use ofthe invention. This content can be adjusted by adjusting the quantity ofnon-polar solvent. The content of the alkyl aluminum partial hydrolyzatecan be adjusted as appropriate within a range of, for example, 1 to 90mass %. However, it is not intended that this content be limited to thisrange. From perspectives such as solubility and viscosity, the contentof the alkyl aluminum partial hydrolyzate preferably falls within therange of 5 to 50 mass %.

The content of the alkyl aluminum partial hydrolyzate is preferably 5mass % or more from the perspectives of drying being difficult becausethe material content is low and the solvent content is high and theamount of discharged solvent to be treated being high, and the contentof the alkyl aluminum partial hydrolyzate is preferably 50 mass % orless from the perspectives of the viscosity increasing and white solidsand the like precipitating during production. However, it is notintended that this content be limited to this range, and the content ofthe alkyl aluminum partial hydrolyzate can be decided as appropriateaccording to the intended use of the invention, and the like.

If it is assumed that all of the aluminum contained in the solutioncontaining the alkyl aluminum partial hydrolyzate of the presentinvention is converted into aluminum oxide (Al₂O₃), the aluminum oxideconversion concentration is defined as the percentage of the mass ofaluminum oxide relative to the mass of the solution containing the alkylaluminum partial hydrolyzate.

The aluminum oxide conversion concentration of the solution containingthe alkyl aluminum partial hydrolyzate of the present invention can beadjusted as appropriate within a range of, for example, 5 to 50 mass %.However, it is not intended that this conversion concentration belimited to this range.

[Method for producing aluminum oxide thin film]

The method for producing an aluminum oxide thin film of the presentinvention is a method in which an aluminum oxide thin film is obtainedby coating a substrate with the solution containing the alkyl aluminumpartial hydrolyzate of the present invention.

The substrate can be coated using a commonly used coating method, suchas a spin coating method, a dip coating method, a screen printingmethod, a bar coating method, a slit coating method, a die coatingmethod, a gravure coating method, a roll coating method, a curtaincoating method, a spray thermal decomposition method, an electrostaticspray thermal decomposition method, an inkjet method or a mist CVDmethod.

The substrate can be coated in an inert gas atmosphere or an airatmosphere.

The substrate can be coated under increased pressure or reducedpressure, but from the perspective of profitability, an apparatus inwhich coating is carried out under atmospheric pressure is preferred dueto the apparatus being simple.

The substrate can be a glass such as a lead glass, a soda glass, aborosilicate glass or an alkali-free glass; an oxide such as silica,alumina, titania, zirconia or a composite oxide; or a polymer such aspolyethylene (PE), polypropylene (PP), poly(ethylene terephthalate)(PET), poly(ethylene naphthalate) (PEN), poly(methyl methacrylate)(PMMA), a polycarbonate (PC), poly(phenylene sulfide) (PPS), polystyrene(PS), poly(vinyl alcohol) (PVA), poly(vinyl chloride) (PVC),poly(vinylidene chloride), a cyclic polyolefin (COP), an ethylene-vinylacetate copolymer (EVA), a polyimide, a polyamide, a polyethersulfone(PES), a polyurethane, triacetate, triacetyl cellulose (TAC),cellophane, polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene(PCTFE), poly(vinylidene fluoride) (PVDF), poly(vinyl fluoride) (PVF), aperfluoroalkoxyfluororesin (PFA), atetrafluoroethylene-hexafluoropropylene copolymer (ETFE) or anethylene-chlorotrifluoroethylene copolymer (ECTFE).

The form of the substrate may be a powder, a film, a sheet or a solidstructure having a three-dimensional form.

The aluminum oxide thin film is formed by coating the solutioncontaining the alkyl aluminum partial hydrolyzate, adjusting thesubstrate to a prescribed temperature, and then firing at a prescribedtemperature either after removing the solvent by drying or whileremoving the solvent by drying. Moreover, in cases where the coating iscarried out using a spray thermal decomposition method, an electrostaticspray thermal decomposition method, an inkjet method or a mist CVDmethod, it is possible to carry out solvent removal at the time ofcoating or carry out firing at the time of solvent removal because thesubstrate can be heated to the prescribed temperature prior to coating.

The prescribed temperature for removing the solvent by drying can beselected as appropriate within a range of, for example, 20° C. to 250°C. The solvent can be removed by drying over a period of, for example,0.5 to 60 minutes. However, it is not intended that these conditions belimited to these ranges.

The prescribed temperature for firing in order to form the aluminumoxide can be selected as appropriate within a range of, for example, 50°C. to 550° C. However, depending on the type of substrate, thetemperature should be set so that the substrate is not damaged. In caseswhere the prescribed temperature for firing is the same as theprescribed temperature for removing the solvent by drying, the solventremoval and the firing can be carried out simultaneously. The driedprecursor film from which the solvent has been removed by drying can befired over a period of, for example, 0.5 to 300 minutes.

The thickness of aluminum oxide thin film obtained in the mannerdescribed above can be, for example, 0.005 to 3 μm. However, it is notintended that this thickness be limited to this range. The thickness ofthe aluminum oxide thin film can be increased if necessary by repeatedlycarrying out the steps of coating, drying and firing mentioned above.

The crystallinity and compactness of the aluminum oxide can, ifnecessary, be improved by heating the aluminum oxide thin film obtainedin the manner described above to a prescribed temperature in anoxidizing gas atmosphere such as oxygen, a reducing gas atmosphere suchas hydrogen, a water vapor atmosphere in which a large quantity of wateris present or a plasma atmosphere such as argon, nitrogen or oxygen.Organic residues and the like present in the obtained aluminum oxidethin film can be removed by irradiating with ultraviolet radiation orthe like or treating with microwaves.

[Method for producing substrate containing particulate aluminum oxide]

The method for producing a substrate containing particulate aluminumoxide of the present invention is a method in which a substratecontaining particulate aluminum oxide is obtained by mixing the solutioncontaining the alkyl aluminum partial hydrolyzate of the presentinvention with the substrate raw material when the substrate isproduced.

When producing the substrate, the substrate raw material and thesolution containing the alkyl aluminum partial hydrolyzate can beintroduced into a production apparatus using any commonly used method.The pressure inside the production apparatus is not limited.

The substrate can be the same as the substrate used when producing thealuminum oxide thin film. The substrate raw material is a material ableto serve as a raw material of these substrates, and is preferably apolymer material.

The aluminum oxide produced using the method for producing an aluminumoxide thin film of the present invention and the particulate aluminumoxide formed in the substrate in the method for producing a particulatealuminum oxide-containing substrate differ in terms of firing,post-treatment conditions, and the like, but are assumed to be gibbsite,bayersite, boehmite or diaspore, which are hydrates, or γ-, η-, δ-, θ-,κ- or α-alumina. In cases where treatment is carried out in a watervapor atmosphere or the like, the aluminum oxide may be converted intoaluminum hydroxide.

Aluminum oxide produced at a temperature of 500° C. or lower in thepresent invention generally has no clear peaks in X-Ray diffractionanalysis, and is in an amorphous state.

[Method for producing polyolefin-based polymer nanocomposite containingzinc oxide particles (first mode of second aspect)]

A first mode of the second aspect of the present invention relates to amethod for producing a polyolefin-based polymer nanocomposite containingzinc oxide particles, the method being characterized by using apolyolefin powder and a solution containing a partial hydrolyzate of adialkyl zinc wherein the alkyl groups may be the same or different andhave 1 to 14 carbon atoms.

More specifically, the first mode of the second aspect of the presentinvention comprises (A) a step of impregnating a polyolefin powder witha solution containing a partial hydrolyzate of a dialkyl zinc whereinthe alkyl groups may be the same or different and have 1 to 12 carbonatoms, (B) a step of removing an organic solvent contained in thepolyolefin powder, and (D) a step of melting the polyolefin powder byheating.

Step (A)

The dialkyl zinc is preferably represented by general formula (2-1)below.

[C6]

ZnR¹⁰ ₂   (2-1)

In the formula, R¹⁰ represents a methyl group, an ethyl group, ann-butyl group, an isobutyl group, a sec-butyl group or a tert-butylgroup. The two R¹⁰ groups may be the same or different.

Examples of compounds represented by general formula (2-1) includedimethyl zinc, diethyl zinc, di-n-butyl zinc, diisobutyl zinc,di-sec-butyl zinc and di-tert-butyl zinc. From the perspective of beinginexpensive in terms of cost per unit mass of zinc, diethyl zinc ispreferred.

The solution containing a partial hydrolyzate is preferably prepared byadding water at a molar ratio of 0.5 to 1.4 relative to zinc in adialkyl zinc to a solution containing the dialkyl zinc and an organicsolvent.

Examples of the organic solvent include aromatic hydrocarbons, aliphatichydrocarbons, ether-based solvents not containing active hydrogen, andother organic solvents.

Examples of aromatic hydrocarbons include benzene, toluene, o-xylene,m-xylene, p-xylene, mixed xylene (xylene), ethylbenzene,isopropylbenzene, mesitylene, pseudocumene, amylbenzene, o-cymene,m-cymene, p-cymene, mixed cymene (cymene), o-diethylbenzene,m-diethylbenzene, p-diethylbenzene, mixed diethylbenzene(diethylbenzene), cyclohexylbenzene and tetralin.

Examples of aliphatic hydrocarbons include pentane, methylcyclopentane,hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, heptane,nonane, octane, n-decane, n-undecane, n-dodecane, tridecane,tetradecane, kerosene, decalin, petroleum ether, petroleum benzine,solvent naphtha, dipentene, turpentine oil, o-menthane, m-menthane,p-menthane, mixed menthane (menthane) and ligroin.

Examples of ether-based solvents not containing active hydrogen includediethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether,tetrahydrofuran, dioxane, anisole, methyl tert-butyl ether,dimethoxyethane and 1,2-diethoxyethane.

Examples of other solvents include ester-based solvents, such as ethylacetate, n-butyl acetate, s-butyl acetate and γ-butyl lactone, andN-methylpyrrolidone.

The dialkyl zinc can be partially hydrolyzed using water. The molarratio of water relative to the dialkyl zinc is not particularly limited,but preferably falls within the range of 0.5 to 1.4, and more preferably0.5 to 0.9. If the molar ratio of water relative to the dialkyl zinc isless than 0.5, residual dialkyl zinc causes the polyolefin to readilyaggregate during impregnation and drying and means that it is difficultto form zinc oxide having an average particle diameter of 100 nm or lessin the polyolefin. Meanwhile, if the molar ratio of water relative tothe dialkyl zinc is excessively high, insoluble gels and solids areprecipitated in the solvent. From the perspective of forming uniformzinc oxide particles in the polyolefin, it is preferable forprecipitated gels and solids to be removed by means of decanting,filtration, or the like.

The partial hydrolysis reaction of the dialkyl zinc is carried out byadding water to the organic solvent in an inert gas atmosphere.

The concentration of the dialkyl zinc in the dialkyl zinc solution towhich water is added can be, for example, 5 to 98 mass %.

The water can be diluted using the organic solvent and added as awater-containing solution.

The water can be added dropwise using a syringe or added using adropping funnel or the like. In addition, it is possible to add thewater as mist-like droplets by bringing the water into contact withpressurized nitrogen or the like using a 2-fluid spray nozzle mechanismor the like.

The period of addition of the water or water-containing solution to thedialkyl zinc solution can be specified as appropriate according to thetypes, volumes, and the like, of the raw materials being mixed, but canfall within the range of 1 minute to 10 hours. The temperature duringthe addition can be selected as appropriate within the range of −20° C.to 150° C. However, this temperature preferably falls within the rangeof −15° C. to 80° C. in view of safety and the like.

Following addition of water or a water-containing solution, an agingreaction can be carried out fora period of 0.1 to 50 hours in order forthe partial hydrolysis reaction between the dialkyl zinc and water toprogress further. The temperature during the aging reaction can beselected as appropriate within the range of −15° C. to 150° C. However,this temperature preferably falls within the range of 25° C. to 150° C.from perspectives such as shortening the aging reaction time.

The dialkyl zinc, water and organic solvent can be introduced into areaction vessel using any commonly used method. The pressure inside thereaction vessel is not limited. The hydrolysis reaction step is notparticularly limited, and can be a batch type process, a semi-batch typeprocess or a continuous process, but a batch type process is preferred.

A solution containing the alkyl zinc partial hydrolyzate is obtained bymeans of this partial hydrolysis reaction. Partial hydrolyzatecompositions have long been analyzed in cases where a dialkyl zinc isdiethyl zinc. However, compositional analysis results of products varyfrom report to report, and product compositions have not been clearlyspecified. In addition, the product composition varies according todifferences in the solvent, the concentration, the added molar ratio ofwater, the addition temperature, the reaction temperature, the reactionperiod, and the like.

It is presumed that the alkyl zinc partial hydrolyzate in the method ofthe present invention is a mixture of compounds including structuralunits represented by general formula (2-3) below.

[C7]

R¹⁰—[Zn—O]_(m)—R¹⁰   (2-3)

In the formula, R¹⁰ is defined in the same way as R¹⁰ in general formula(2-1), and m is an integer between 1 and 20.

In cases where solids and the like are precipitated following completionof the partial hydrolysis reaction, the solids and the like can beremoved through purification by means of a method such as filtration.

The solid content concentration in the solution containing the alkylzinc partial hydrolyzate can be adjusted by means of concentrating(solvent removal). In addition, the solid content concentration,polarity, viscosity, boiling point, profitability, and the like, can beadjusted as appropriate by adding the solvent used in the reaction or anorganic solvent that is different from that used in the reaction.

The content of the alkyl zinc partial hydrolyzate in the solutioncontaining the alkyl zinc partial hydrolyzate of the present inventioncan be decided as appropriate. This content can be adjusted by adjustingthe quantity of organic solvent. The content of the alkyl zinc partialhydrolyzate can be adjusted as appropriate within a range of, forexample, 5 to 90 mass %. However, it is not intended that this contentbe limited to this range. From perspectives such as solubility andviscosity, the content of the alkyl zinc partial hydrolyzate preferablyfalls within the range of 5 to 50 mass %.

The content of the alkyl zinc partial hydrolyzate is preferably 5 mass %or more from the perspectives of drying being difficult because thematerial content is low and the solvent content is high and the amountof discharged solvent to be treated being high. The content of the alkylaluminum partial hydrolyzate is preferably 50 mass % or less from theperspectives of the viscosity increasing and white solids and the likeprecipitating during production.

If it is assumed that all of the zinc contained in the solutioncontaining the alkyl zinc partial hydrolyzate is converted into zincoxide (ZnO), the zinc oxide conversion concentration in the solutioncontaining the alkyl zinc partial hydrolyzate is defined as thepercentage of the mass of zinc oxide relative to the mass of thesolution containing the alkyl zinc partial hydrolyzate.

The zinc oxide conversion concentration of the solution containing thealkyl zinc partial hydrolyzate can be adjusted as appropriate within arange of, for example, 5 to 40 mass %.

Examples of polyolefins that constitute the polyolefin powder includeethylene homopolymers; ethylene copolymers obtained by polymerizingethylene and at least one type selected from propylene and a-olefinshaving 4 to 8 carbon atoms; propylene homopolymers; and propylenecopolymers obtained by polymerizing propylene and at least one typeselected from ethylene and a-olefins having 4 to 8 carbon atoms. Thesepolyolefins may contain, as second and third comonomers, smallquantities of dienes, vinyl acetate, unsaturated carboxylic acids,unsaturated carboxylic acid esters, and aromatic monomers such asstyrene and styrene derivatives. In the present invention, polyethyleneis defined as the ethylene homopolymer and ethylene copolymers mentionedabove, and polypropylene is defined as the polypropylene homopolymer andpropylene copolymers mentioned above.

Examples of methods for producing the polyolefin powder of the presentinvention include the Ziegler-Natta process, a metallocene process andhigh pressure radical polymerization methods. However, it is notintended that the production method be limited to the methods mentionedabove. The polyolefin powder is preferably porous from the perspectiveof reliably enabling impregnation by the solution containing the alkylzinc partial hydrolyzate. From the perspective of being able to obtain aporous polyolefin powder, the method for producing the polyolefin powderis preferably the Ziegler-Natta process. The polyolefin powder used inthe present invention is preferably a powder obtained using theZiegler-Natta process.

The polyolefin is preferably in the form of a powder from theperspective of facilitating impregnation by the solution containing thealkyl zinc partial hydrolyzate. Furthermore, the diameter of particlesconstituting the powder is preferably relatively small from theperspective of the solution containing the alkyl zinc partialhydrolyzate impregnating into the inner part of the particles and beingable to obtain a nanocomposite in which zinc oxide particles are in awell dispersed state. The average particle diameter of particlesconstituting the powder should fall within a range of, for example, 0.1to 1000 μm. However, it is not intended that this average particlediameter be limited to this range.

The polyolefin particles are preferably porous from the perspective offacilitating impregnation by the solution containing the alkyl zincpartial hydrolyzate. As an indicator of porosity, the density (bulkdensity) should fall within a range of, for example, 0.8 to 1.0 g/cm³.However, it is not intended that this density be limited to this range.

Impregnation of the solution containing the alkyl zinc partialhydrolyzate into the polyolefin powder is preferably carried out in areducing atmosphere or inert atmosphere, and more preferably carried outin a nitrogen atmosphere from the perspective of profitability.

The polyolefin powder can be impregnated under increased pressure orreduced pressure, but from the perspective of profitability, anapparatus in which impregnation is carried out under atmosphericpressure is preferred due to the apparatus being simple.

Aging can be carried out for a period of 0.1 to 50 hours in order forthe polyolefin powder to be uniformly impregnated. The aging temperaturecan be selected as appropriate within the range of −15° C. to 100° C.However, this temperature preferably falls within the range of 25° C. to100° C. from perspectives such as shortening the aging time.

In this step, it is possible to add an antioxidant to the solutioncontaining the partial hydrolyzate that is impregnated in the polyolefinpowder in order to prevent thermal degradation of the polyolefin in themelting and heating step (D) described later. Alternatively, it ispossible to simultaneously impregnate the polyolefin powder with asolution containing a partial hydrolyzate and a solution containing anantioxidant. Alternatively, it is possible to impregnate the polyolefinpowder with a solution containing a partial hydrolyzate and thenimpregnate the polyolefin powder with a solution containing anantioxidant. The solution containing an antioxidant can be one obtainedby dissolving an antioxidant in an organic solvent listed for thesolution containing a partial hydrolyzate. It is possible to use apublicly known antioxidant for polyolefins, as appropriate, as theantioxidant. The quantity of antioxidant added to the polyolefin powdercan fall within a range of, for example, 0.01 to 1 mass % according tothe type of antioxidant and type of polyolefin. However, it is notintended that this added quantity be limited to this range.

Examples of antioxidants include phenol-based antioxidants such as1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione,4,4′, 4″-(1-methylpropanyl-3-ylidene)tris(6-t-butyl-m-cresol),6,6′-di-t-butyl-4,4′-butylidenedi-m-cresol, octadecyl3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecaneand 1,3,5-t-tris(3,5-di-t-butyl-4-hydroxyphenyl)-2,4,6-trimethylbenzene.

(B) Organic solvent removal step

In step (B), organic solvent contained in the solution containing thepartial hydrolyzate is removed from the polyolefin powder. The organicsolvent removal is not particularly limited as long as organic solventcan be removed from the polyolefin powder obtained in step (A). Forexample, organic solvent removal can be carried out by drying thepolyolefin powder obtained in step (A) at a prescribed temperature. Itis possible to select an appropriate temperature within a range of, forexample, 20° C. to 100° C., and the drying can be carried out atatmospheric pressure or under reduced pressure. It is preferable for thetemperature to be 100° C. or lower and for the pressure to be reducedfrom the perspective of preventing the polyolefin from melting prior toremoving the solvent. The solvent can be removed by drying over a periodof, for example, 0.5 minutes to 50 hours. However, it is not intendedthat these conditions be limited to these ranges.

(D) Melting and heating step

After carrying out the organic solvent removal step, impregnation iscarried out at a temperature that is not lower than the melting point ofthe polyolefin using a type of mixer or extruder, and the polyolefinpowder from which the solvent has been removed by drying is then meltkneaded. The melt kneading temperature can be decided as appropriateaccording to the type of polyolefin in view of the melting pointthereof. For example, the melt kneading temperature is preferably 120°C. to 150° C. in the case of polyethylene and 160° C. to 200° C. in thecase of polypropylene from the perspective of minimizing thermaldegradation. The melt kneading can be carried out over a period of, forexample, 1 minute to 50 hours. However, it is not intended that theseconditions be limited to these ranges.

Through melting the polyolefin powder by heating, it is possible toobtain a polyolefin-based polymer nanocomposite containing zinc oxideparticles. The content (concentration) of zinc oxide particles in apolyolefin-based polymer nanocomposite produced using the productionmethod of the present invention is not particularly limited. However, itis preferable for the content of zinc oxide particles to be 3 wt % ormore. If this content is less than 3 wt %, the advantageous effect ofthe zinc oxide is unlikely to be exhibited. However, if the upper limitof this content exceeds, for example, 40 wt %, the characteristics ofthe polyolefin are likely to be lost and costs tend to increase as aresult of an increase in the quantity of zinc oxide. From perspectivessuch as these, it is preferable for the concentration of the zinc oxideparticles to be adjusted as appropriate within the range of 3 to 40 wt%.

In the present invention, the zinc oxide content (concentration) in thenanocomposite is defined as the percentage of the mass of zinc oxiderelative to the total mass of the polyolefin nanocomposite containingzinc oxide.

It is possible to produce a polyolefin nanocomposite containing zincoxide by melt kneading, and then further heating, molding or granulatingaccording to need. The form of the polyolefin nanocomposite can be asheet, a film, chips, and the like, but is not particularly limited.

It is assumed that by carrying out steps (A), (B) and (D), the alkylzinc partial hydrolyzate is converted into zinc oxide in the polyolefinas a result of a reaction represented by general formula (2-4) below.

[C8]

R¹⁰—[Zn—O]_(m)—R¹⁰−>m ZnO   (2-4)

In the formula, R¹⁰ is defined in the same way as R¹⁰ in general formula(2-1), and m is an integer between 1 and 20.

(C) Moisture supply step

Between the organic solvent removal step (B) and the melting and heatingstep (D), it is possible to incorporate a step (C) of supplying moistureto the alkyl zinc partial hydrolyzate contained in the polyolefin powderto facilitate hydrolysis.

Examples of methods for supplying moisture include spraying thepolyolefin powder, which has been impregnated and dried by removing thesolvent, into air for a sufficient period of time, bringing thepolyolefin powder into contact with water vapor in a container such as achamber, exposing the polyolefin powder to moist air in a container suchas a chamber, and bringing water directly into contact with thepolyolefin powder.

A reaction with moisture is preferably carried out at 20° C. to 100° C.when moisture is supplied. The moisture supply can be carried out over aperiod of, for example, 0.5 minutes to 50 hours. However, it is notintended that these conditions be limited to these ranges.

[Polyolefin-based polymer nanocomposite containing zinc oxide particles]

The present invention encompasses a polyolefin-based polymernanocomposite, which contains a polyolefin base material and zinc oxideparticles and does not contain a dispersing agent, in which the averageparticle diameter of the zinc oxide particles is less than 100 nm. Thispolyolefin-based polymer nanocomposite can be produced using theproduction method of the present invention. The average particlediameter of zinc oxide particles in the polyolefin preferably fallswithin the range of not less than 1 nm and less than 100 nm. Thepolyolefin-based polymer nanocomposite of the present invention is ananocomposite in which zinc oxide particles are dispersed well in a basematerial without using a dispersing agent (without using a dispersingagent as an auxiliary dispersing agent for the zinc oxide particles)despite using a polyolefin-based polymer, in which oxide particles aredifficult to disperse, as the base material, and despite the averageparticle diameter of the zinc oxide particles being extremely low,namely less than 100 nm.

Moreover, in the present invention, the dispersing agent that is notcontained in the nanocomposite refers to a chemical agent that is usedin order to disperse the zinc oxide particles in the polyolefin basematerial. Additives described later, which are subsequently added to thenanocomposite and which have the effect of dispersing inorganicparticles, do not correspond to the meaning of the dispersing agentmentioned here. Ultimately, this means that a dispersing agent used todisperse zinc oxide particles in the polyolefin base material is notused in the process for producing the nanocomposite, meaning that thenanocomposite of the present invention does not contain a dispersingagent.

The content (concentration) of zinc oxide particles in the polyolefin isnot particularly limited, but can be, for example, 3 wt % or more. Thezinc oxide content (concentration) in the nanocomposite is defined asthe percentage of the mass of zinc oxide relative to the total mass ofthe polyolefin nanocomposite containing zinc oxide of the presentinvention.

The advantageous effect of the zinc oxide is unlikely to be exhibited ifthis content is less than 3 wt %, and if this content is 40 wt % ormore, the characteristics of the polyolefin are likely to be lost andcosts tend to increase as a result of an increase in the quantity ofzinc oxide. From perspectives such as these, it is preferable for theconcentration of the zinc oxide to be adjusted as appropriate within therange of 3 to 40 wt %.

The crystallinity and crystal form of the zinc oxide can, if necessary,be improved by heating the zinc oxide in the polyolefin obtained in themanner described above to a prescribed temperature in an oxidizing gasatmosphere such as oxygen, a reducing gas atmosphere such as hydrogen,or a plasma atmosphere such as argon, nitrogen or oxygen. Thecrystallinity and crystal form of the zinc oxide can also be improved byirradiating with ultraviolet radiation or the like or treating withmicrowaves.

The polyolefin nanocomposite containing zinc oxide particles of thepresent invention can improve basic characteristics of a polymer as amatrix, for example, can improve thermal stability and abrasionresistance, can adjust refractive index, and can improve stabilityagainst ultraviolet radiation, to impart functionality such aselectrical conductivity, ultraviolet radiation absorption, antibacterialproperties and refractive index adjustment. Therefore, it is expectedthat this polyolefin nanocomposite containing zinc oxide particles willbe used as a replacement product for materials of existing products thatrequire thermal stability, abrasion resistance, increased refractiveindex, stability against ultraviolet radiation, electrical conductivity,ultraviolet radiation absorption, antibacterial properties or refractiveindex adjustment.

The polyolefin nanocomposite containing zinc oxide particles of thepresent invention may contain a variety of additives as long as theadvantageous effect of the zinc oxide particles contained in thecomposite is not impaired. Examples of such additives includeplasticizers such as poly(alkylene oxide) oligomer-based compounds andorganic phosphorus-based compounds, crystal nucleating agents such astalc, kaolin and organic phosphorus-based compounds, montanic acidwaxes, metal soaps such as lithium stearate and aluminum stearate,lubricants, ultraviolet radiation blocking agents, coloring agents,flame retardants and foaming agents. These additives may be subsequentlyadded to the polyolefin nanocomposite containing zinc oxide particles,but may also be added, for example, after the zinc oxide particles aredispersed in the polyolefin base material in the melting and heatingstep (D) that is the nanocomposite preparation step.

[Method for producing polyolefin-based polymer nanocomposite containingaluminum oxide particles (second mode of second aspect)]

The second mode of second aspect of the present invention is a methodfor producing a polyolefin-based polymer nanocomposite which containsaluminum oxide particles, the method being characterized by using apolyolefin powder and a solution containing a partial hydrolyzate of analkyl aluminum compound comprising a trialkyl aluminum or a mixturethereof (here, the alkyl groups may be the same or different and have 1to 12 carbon atoms).

More specifically, the second mode of the second aspect of the presentinvention comprises (E) a step of impregnating a polyolefin powder witha solution containing a partial hydrolyzate of an alkyl aluminumcompound comprising a trialkyl aluminum or a mixture thereof (here, thealkyl groups may be the same or different and have 1 to 12 carbonatoms), (F) a step of removing an organic solvent contained in thepolyolefin powder, and (H) a step of melting the polyolefin powder byheating.

(E) Impregnation step

The trialkyl aluminum is preferably a trialkyl aluminum represented bygeneral formula (2-2) below.

[C9]

AlR² ₃   (2-2)

In the formula, R² represents a methyl group, an ethyl group, anisobutyl group, a n-hexyl group or an n-octyl group. The three R² groupsmay be the same or different.

Examples of the compound represented by general formula (2-2) includetrimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tri-n-hexylaluminum, tri-n-octyl aluminum, tridodecyl aluminum and tritetradecylaluminum. From the perspective of being inexpensive in terms of cost perunit mass of aluminum, trimethyl aluminum, triethyl aluminum andtriisobutyl aluminum are preferred, and triethyl aluminum andtriisobutyl aluminum are particularly preferred.

The solution containing a trialkyl aluminum partial hydrolyzate ispreferably prepared by adding water at a molar ratio of 0.5 to 1.4relative to aluminum in a trialkyl aluminum to a solution containing thetrialkyl aluminum and an organic solvent. If the molar ratio of waterrelative to the trialkyl aluminum is less than 0.5, residual trialkylaluminum causes the polyolefin to readily aggregate during impregnationand drying and means that it is difficult to form aluminum oxide havingan average particle diameter of 100 nm or less in the polyolefin.Meanwhile, if the molar ratio of water relative to the trialkyl aluminumexceeds 1.4, insoluble gel or solid precipitates in the solvent and itis difficult to form uniform aluminum oxide particles in the polyolefindue to the presence of the gel or solid, and this molar ratio istherefore preferably 1.4 or less, and more preferably 1.3 or less.Precipitated gel or solid can be removed by means of decanting,filtration or the like.

Examples of the organic solvent include compounds similar to those usedwhen producing the polyolefin nanocomposite containing zinc oxide.

The partial hydrolysis reaction of the trialkyl aluminum is carried outby adding water to the organic solvent in an inert gas atmosphere.

The concentration of the trialkyl aluminum in the trialkyl aluminumsolution to which the water is added can be 5 to 98 mass %.

The water can be diluted using the organic solvent and added as awater-containing solution.

The water can be added dropwise using a syringe, a dropping funnel, orthe like. In addition, it is possible to add the water as mist-likedroplets by bringing the water into contact with pressurized nitrogen orthe like using a 2-fluid spray nozzle mechanism or the like.

The period of addition of the water or water-containing solution to thetrialkyl aluminum solution can be specified as appropriate according tothe types, volumes, and the like, of the raw materials being mixed, butcan fall within the range of 1 minute to 10 hours. The temperatureduring the addition can be selected as appropriate within the range of−20° C. to 150° C. However, this temperature preferably falls within therange of −15° C. to 80° C. in view of safety and the like.

Following addition of water or a water-containing solution, an agingreaction can be carried out for a period of 0.1 to 50 hours in order forthe partial hydrolysis reaction between the trialkyl aluminum and waterto progress further. The temperature during the aging reaction can beselected as appropriate within the range of −15° C. to 150° C.

The trialkyl aluminum, water and organic solvent can be introduced intoa reaction vessel using any commonly used method. The pressure insidethe reaction vessel is not limited. The hydrolysis reaction step is notparticularly limited, and can be a batch type process, a semi-batch typeprocess or a continuous process, but a batch type process is preferred.

A solution containing the alkyl aluminum partial hydrolyzate is obtainedby means of this partial hydrolysis reaction. Alkyl aluminum partialhydrolyzate compositions have long been analyzed, but compositionalanalysis results of products vary from report to report, and productcompositions have not been clearly specified. In addition, the productcomposition varies according to differences in the solvent, theconcentration, the added molar ratio of water, the addition temperature,the reaction temperature, the reaction period, and the like.

It is presumed that the alkyl aluminum partial hydrolyzate in the methodof the present invention is a mixture of compounds including structuralunits represented by general formula (2-5) below.

(In the formula, R² is defined in the same way as R² in general formula(2-2), and m is an integer between 1 and 80.)

In cases where solids and the like are precipitated following completionof the partial hydrolysis reaction, the solids and the like can beremoved through purification by means of a method such as filtration.

The solid content concentration in the solution containing the alkylaluminum partial hydrolyzate can be adjusted by means of concentrating(solvent removal). In addition, the solid content concentration,polarity, viscosity, boiling point, profitability, and the like, can beadjusted as appropriate by adding the solvent used in the reaction or anorganic solvent that is different from that used in the reaction.

The content of the alkyl aluminum partial hydrolyzate in the solutioncontaining the alkyl aluminum partial hydrolyzate can be decided asappropriate. This content can be adjusted by adjusting the quantity oforganic solvent. The content of the alkyl aluminum partial hydrolyzatecan be adjusted as appropriate within a range of, for example, 5 to 90mass %. However, it is not intended that this content be limited to thisrange. From perspectives such as solubility and viscosity, the contentof the alkyl aluminum partial hydrolyzate preferably falls within therange of 5 to 70 mass %.

The content of the alkyl aluminum hydrolyzate is preferably 5 mass % ormore from the perspectives of drying being difficult because thematerial content is low and the solvent content is high and the amountof discharged solvent to be treated being high, and the content of thealkyl aluminum partial hydrolyzate is preferably 70 mass % or less fromthe perspectives of viscosity increasing and white solids and the likeprecipitating during production.

If it is assumed that all of the aluminum contained in the solutioncontaining the alkyl aluminum hydrolyzate is converted into aluminumoxide (Al₂O₃), the aluminum oxide conversion concentration in thesolution containing the alkyl aluminum partial hydrolyzate is defined asthe percentage of the mass of aluminum oxide relative to the mass of thesolution containing the alkyl aluminum partial hydrolyzate.

The aluminum oxide conversion concentration of the solution containingthe alkyl aluminum partial hydrolyzate can be adjusted as appropriatewithin a range of, for example, 5 to 40 mass %.

Examples of the polyolefin powder include polyolefin powders similar tothat used when producing the polyolefin nanocomposite containing zincoxide particles.

Impregnation of the solution containing the alkyl aluminum partialhydrolyzate into the polyolefin powder is preferably carried out in areducing atmosphere or inert atmosphere, and more preferably carried outin a nitrogen atmosphere from the perspective of profitability.

The polyolefin powder can be impregnated under increased pressure orreduced pressure, but from the perspective of profitability, anapparatus in which impregnation is carried out under atmosphericpressure is preferred due to the apparatus being simple.

Aging can be carried out fora period of 0.1 to 50 hours in order for thepolyolefin powder to be uniformly impregnated. The aging temperature canbe selected as appropriate within the range of −15° C. to 100° C.However, this temperature preferably falls within the range of 25° C. to100° C. from perspectives such as shortening the aging time.

In this step, it is preferable to add an antioxidant in order to preventthermal degradation of the polyolefin in the melting and heating step(H) described later. It is possible to use a publicly known antioxidantfor polyolefins as the antioxidant.

Examples of the antioxidant include antioxidants similar to that usedwhen producing the polyolefin nanocomposite containing zinc oxide.

The aluminum oxide concentration in the nanocomposite is defined as thepercentage of the mass of aluminum oxide relative to the total mass ofthe polyolefin nanocomposite containing aluminum oxide of the presentinvention.

The advantageous effect of the aluminum oxide is unlikely to beexhibited if this content is less than 3 wt %, and if this content is 40wt % or more, the characteristics of the polyolefin are likely to belost and costs tend to increase as a result of an increase in thequantity of aluminum oxide. From perspectives such as these, it ispreferable for the concentration of the aluminum oxide to be adjusted asappropriate within the range of 3 to 40 wt %.

(F) Organic solvent removal step

In step (F), organic solvent contained in the solution containing thepartial hydrolyzate is removed from the polyolefin powder. The organicsolvent removal is not particularly limited as long as organic solventcan be removed from the polyolefin powder obtained in step (E). Forexample, organic solvent removal can be carried out by drying thepolyolefin powder obtained in step (E) at a prescribed temperature. Forthe prescribed temperature for removing the organic solvent, it ispossible to select a temperature as appropriate within a range of, forexample, 20° C. to 100° C., and the drying can be carried out atatmospheric pressure or under reduced pressure. It is preferable for thetemperature to be 100° C. or lower and the pressure to be reduced fromthe perspective of preventing the polyolefin from melting prior toremoving the solvent. The solvent can be removed by drying over a periodof, for example, 0.5 minutes to 50 hours. However, it is not intendedthat these conditions be limited to these ranges.

(H) Melting and heating step

After carrying out the organic solvent removal step, impregnation iscarried out at a temperature that is not lower than the melting point ofthe polyolefin using a type of mixer or extruder, and the polyolefinpowder from which the solvent has been removed by drying is then meltkneaded. The melt kneading temperature is preferably 120° C. to 150° C.in the case of polyethylene and 160° C. to 200° C. in the case ofpolypropylene from the perspective of minimizing thermal degradation.The melt kneading can be carried out over a period of, for example, 1minute to 50 hours. However, it is not intended that these conditions belimited to these ranges.

Through melting the polyolefin powder by heating, it is possible toobtain a polyolefin-based polymer nanocomposite containing aluminumoxide particles. The content of aluminum oxide particles in apolyolefin-based polymer nanocomposite produced using the productionmethod of the present invention is not particularly limited. However, itis preferable for the content of aluminum oxide particles to be 3 wt %or more. If this content is less than 3 wt %, the advantageous effect ofthe aluminum oxide is unlikely to be exhibited. However, if the upperlimit of this content exceeds, for example, 40 wt %, the characteristicsof the polyolefin are likely to be lost and costs tend to increase as aresult of an increase in the quantity of aluminum oxide. Fromperspectives such as these, it is preferable for the content(concentration) of the aluminum oxide particles to be adjusted asappropriate within the range of 3 to 40 wt %.

In the present invention, the aluminum oxide content (concentration) inthe nanocomposite is defined as the percentage of the mass of aluminumoxide relative to the total mass of the polyolefin nanocompositecontaining aluminum oxide.

A polyolefin nanocomposite containing aluminum oxide is produced by meltkneading and then further heating, molding or granulating. The form ofthe polyolefin nanocomposite can be a sheet, a film, chips, and thelike.

It is assumed that by carrying out steps (E), (F) and (H), the alkylaluminum partial hydrolyzate is converted into aluminum oxide in thepolyolefin as a result of a reaction represented by general formula(2-6) below.

In the formula, R² is defined in the same way as R² in general formula(2-2), and m is an integer between 1 and 80.

(G) Moisture supply step

Between the organic solvent removal step (F) and the melting and heatingstep (H), it is possible to incorporate a step (G) of supplying moistureto the alkyl aluminum partial hydrolyzate contained in the polyolefinpowder to facilitate hydrolysis.

Examples of the method for supplying moisture include supply methodssimilar to that used when producing the polyolefin nanocompositecontaining zinc oxide.

A reaction with moisture is preferably carried out at 20° C. to 100° C.when moisture is supplied. The moisture supply can be carried out over aperiod of, for example, 0.5 minutes to 50 hours. However, it is notintended that these conditions be limited to these ranges.

[Polyolefin-based polymer nanocomposite containing aluminum oxideparticles]

The present invention is a polyolefin-based polymer nanocomposite, whichcontains a polyolefin base material and aluminum oxide particles anddoes not contain a dispersing agent, in which the average particlediameter of the aluminum oxide particles is less than 100 nm.

This polyolefin-based polymer nanocomposite can be produced using theproduction method of the present invention. The average particlediameter of aluminum oxide particles in the polyolefin preferably fallswithin the range of not less than 1 nm and less than 100 nm. Thepolyolefin-based polymer nanocomposite of the present invention is ananocomposite in which aluminum oxide particles are dispersed well in abase material without using a dispersing agent (without using adispersing agent as an auxiliary dispersing agent for the aluminum oxideparticles) despite using a polyolefin-based polymer, in which oxideparticles are difficult to disperse, as the base material, and despitethe average particle diameter of the aluminum oxide particles beingextremely fine, namely less than 100 nm.

Moreover, in the present invention, the dispersing agent that is notcontained in the nanocomposite means a chemical agent that is used inorder to disperse the aluminum oxide particles in the polyolefin basematerial. Additives described later, which are subsequently added to thenanocomposite and which have the effect of dispersing inorganicparticles, do not correspond to the meaning of the dispersing agentmentioned here. Ultimately, this means that a dispersing agent used todisperse aluminum oxide particles in the polyolefin base material is notused in the process for producing the nanocomposite, meaning that thenanocomposite of the present invention does not contain a dispersingagent.

The content of aluminum oxide particles contained in the polyolefinobtained in the manner described above is not particularly limited, butcan be, for example, 3 wt % or more. The aluminum oxide content(concentration) in the nanocomposite is defined as the percentage of themass of aluminum oxide relative to the total mass of the polyolefinnanocomposite containing aluminum oxide of the present invention.

It is preferable to adjust the aluminum oxide concentration within therange of 3 to 40 wt % as appropriate because the advantageous effect ofthe aluminum oxide is unlikely to be exhibited if this content is lessthan 3 wt %, and if this content is 40 wt % or more, the characteristicsof the polyolefin are likely to be lost and costs tend to increase as aresult of an increase in the quantity of aluminum oxide.

The crystallinity and crystal form of the aluminum oxide can, ifnecessary, be improved by heating the aluminum oxide in the polyolefinobtained in the manner described above to a prescribed temperature in anoxidizing gas atmosphere such as oxygen, a reducing gas atmosphere suchas hydrogen, or a plasma atmosphere such as argon, nitrogen or oxygen.The crystallinity and crystal form of the aluminum oxide can be improvedby irradiating with ultraviolet radiation or the like or treating withmicrowaves.

It is known that aluminum oxide is generally in the form of gibbsite,bayersite, boehmite or diaspore, which are hydrates, or χ-, γ-, η-, δ-,θ-, κ- or α-alumina.

The aluminum oxide in the polyolefin produced in the present inventionis a compound which contains aluminum element and oxygen element and inwhich these two elements account for 90% or more of the aluminum oxide.

The form of the aluminum oxide in the present invention differsaccording to post-treatment conditions and the like, but is assumed tobe any of the well-known aluminum oxide forms mentioned above, dependingon treatment temperatures and conditions. In addition, in cases wherethe moisture supply step (G) or the like is carried out, a part of thealuminum oxide may be converted into aluminum hydroxide.

Aluminum oxide produced at a temperature of 500° C. or lower in thepresent invention generally has no clear peaks in powder X-Raydiffraction analysis, and is in an amorphous state.

The polyolefin nanocomposite containing aluminum oxide particles of thepresent invention can impart functionality such as thermal conductivity,abrasion resistance and refractive index adjustment even in a polyolefinnanocomposite containing aluminum oxide particles. Therefore, it isexpected that this polyolefin nanocomposite containing aluminum oxideparticles will be used as a replacement product for materials ofexisting products that require thermal and electrical conductivity,abrasion resistance or refractive index adjustment.

The polyolefin nanocomposite containing aluminum oxide particles of thepresent invention may contain a variety of additives as long as theadvantageous effect of the aluminum oxide particles contained in thenanocomposite is not impaired. Examples of such additives includeplasticizers such as poly(alkylene oxide) oligomer-based compounds andorganic phosphorus-based compounds, crystal nucleating agents such astalc, kaolin and organic phosphorus-based compounds, montanic acidwaxes, metal soaps such as lithium stearate and aluminum stearate,lubricants, ultraviolet radiation blocking agents, coloring agents,flame retardants and foaming agents.

EXAMPLES

The present invention will now be explained in further detail on thebasis of examples. However, the examples are merely examples of thepresent invention, and the present invention is not intended to belimited to the examples.

(First Aspect of Present Invention)

Preparation of the solution containing an alkyl aluminum compound and ofthe solution containing an alkyl aluminum partial hydrolyzate in thepresent invention were carried out in a nitrogen gas atmosphere, withall solvents being dehydrated and degassed.

<Number of Moles of Trialkyl Aluminum>

The number of moles of trialkyl aluminum was calculated using thefollowing formula.

[Number of moles of trialkyl aluminum]=[mass (g) of trialkyl aluminumintroduced]/[molecular weight of trialkyl aluminum (198.33 in the caseof triisobutyl aluminum)]

<Measurement of Physical Properties>

The solution containing an alkyl aluminum partial hydrolyzate of thepresent invention was dried by removing solvent using an evaporator, andthen subjected to transmission IR measurements using a FT-IRspectrophotometer (“FT/IR-4100” available from JASCO Corporation).

Aluminum oxide thin films produced using the production method of thepresent invention were subjected to relative IR measurements without ATRcorrection by means of an ATR (Attenuated Total Reflection) method usinga ZnSe prism in a FT-IR spectrophotometer (“FT/IR-4100” available fromJASCO Corporation).

Synthesis Example 1-1

12.90 g of triisobutyl aluminum (available from Tosoh FinechemCorporation) was added to 10.00 g of toluene at 20° C. and thoroughlystirred. Next, 1.289 g of water ([water]/[triisobutyl aluminum]=1.1(molar ratio)) was added dropwise at 20° C. over a period of 30 minutesusing a syringe. An aging reaction was carried out by continuing to stirfor 3 hours at 25° C., and a small quantity of a precipitated solid wasremoved by being decanted, thereby obtaining a toluene solutioncontaining a triisobutyl aluminum hydrolyzate composition.

The solvent was removed from the obtained toluene solution containing atriisobutyl aluminum hydrolyzate composition by drying for a period of30 minutes at 40° C. using an evaporator, and a spectrum such as thatshown in FIG. 1 was obtained when the obtained composition was subjectedto transmission IR measurements. A broad Al—O—Al vibration peak wasobserved in the region of 400 to 1500 cm⁻¹, and it was confirmed thatAl—O—Al bonds were formed as a result of hydrolysis.

Synthesis Example 1-2

21.61 g of triisobutyl aluminum was added to 10.00 g of toluene at 20°C. and thoroughly stirred. Next, 2.159 g of water ([water]/[triisobutylaluminum]=1.1 (molar ratio)) was added dropwise at 20° C. over a periodof 30 minutes using a syringe. Furthermore, an aging reaction wascarried out by continuing to stir for 3 hours at 25° C., and a smallquantity of a precipitated solid was removed by being decanted, therebyobtaining a toluene solution containing a triisobutyl aluminumhydrolyzate composition.

Synthesis Example 1-3

15.00 g of tri-n-hexyl aluminum (available from Tosoh FinechemCorporation) was added to 1.990 g of toluene at 20° C. and thoroughlystirred. Next, 1.052 g of water ([water]/[tri-n-hexyl aluminum]=1.2(molar ratio)) was added dropwise at 20° C. over a period of 30 minutesusing a syringe. Furthermore, an aging reaction was carried out bycontinuing to stir for 3 hours at 25° C., and a small quantity of aprecipitated solid was removed by being decanted, thereby obtaining atoluene solution containing a tri-n-hexyl aluminum hydrolyzatecomposition.

Synthesis Example 1-4

15.01 g of tri-n-octyl aluminum (available from Tosoh FinechemCorporation) was added to 4.890 g of toluene at 20° C. and thoroughlystirred. Next, 0.958 g of water ([water]/[tri-n-octyl aluminum]=1.3(molar ratio)) was added dropwise at 20° C. over a period of 30 minutesusing a syringe. Furthermore, an aging reaction was carried out bycontinuing to stir for 3 hours at 25° C., and a small quantity of aprecipitated solid was removed by being decanted, thereby obtaining atoluene solution containing a tri-n-octyl aluminum hydrolyzatecomposition.

The solvent was removed from the obtained toluene solution containing atri-n-octyl aluminum hydrolyzate composition by drying for a period of30 minutes at 40° C. using an evaporator, and a spectrum such as thatshown in FIG. 2 was obtained when the obtained composition was subjectedto transmission IR measurements. A broad Al—O—Al vibration peak wasobserved in the region of 400 to 1500 cm⁻¹, and it was confirmed thatAl—O—Al bonds were formed as a result of hydrolysis.

Synthesis Example 1-5

12.18 g of triisobutyl aluminum was added to 10.70 g of decane at 20° C.and thoroughly stirred. Next, 1.326 g of water ([water]/[triisobutylaluminum]=1.2 (molar ratio)) was added dropwise at 20° C. over a periodof 30 minutes using a syringe. Furthermore, an aging reaction wascarried out by continuing to stir for 3 hours at 25° C., and a smallquantity of a precipitated solid was removed by being decanted, therebyobtaining a decane solution containing a triisobutyl aluminumhydrolyzate composition.

The solvent was removed from the obtained decane solution containing atriisobutyl aluminum hydrolyzate composition by drying for a period of30 minutes at 40° C. using an evaporator, and a spectrum such as thatshown in FIG. 3 was obtained when the obtained composition was subjectedto transmission IR measurements. A broad Al—O—Al vibration peak wasobserved in the region of 400 to 1500 cm⁻¹, and it was confirmed thatAl—O—Al bonds were formed as a result of hydrolysis.

Synthesis Example 1-6

15.00 g of tri-n-octyl aluminum was added to 4.890 g of decane at 20° C.and thoroughly stirred. Next, 0.958 g of water ([water]/[tri-n-octylaluminum]=1.3 (molar ratio)) was added dropwise at 20° C. over a periodof 30 minutes using a syringe. Furthermore, an aging reaction wascarried out by continuing to stir for 3 hours at 25° C., and a smallquantity of a precipitated solid was removed by being decanted, therebyobtaining a decane solution containing a tri-n-octyl aluminumhydrolyzate composition.

The solvent was removed from the obtained decane solution containing atri-n-octyl aluminum hydrolyzate composition by drying for a period of30 minutes at 40° C. using an evaporator, and a spectrum such as thatshown in FIG. 4 was obtained when the obtained composition was subjectedto transmission IR measurements. A broad Al—O—Al vibration peak wasobserved in the region of 400 to 1500 cm⁻¹, and it was confirmed thatAl—O—Al bonds were formed as a result of hydrolysis.

Reference Synthesis Example 1-1

12.09 g of triisobutyl aluminum was added to 10.00 g of tetrahydrofuran(hereinafter referred to as THF) at 20° C. and thoroughly stirred. Next,1.208 g of water ([water]/[triisobutyl aluminum]=1.1 (molar ratio)) wasadded dropwise at 20° C. over a period of 30 minutes using a syringe.Furthermore, an aging reaction was carried out by continuing to stir for3 hours at 25° C., and a THF solution containing a triisobutyl aluminumhydrolyzate composition was obtained.

Reference Synthesis Example 1-2

10.90 g of triethyl aluminum was added to 17.41 g of toluene at 20° C.and thoroughly stirred. Next, 1.891 g of water ([water]/[triisobutylaluminum]=1.1 (molar ratio)) was added dropwise at 20° C. over a periodof 30 minutes using a syringe. However, by-produced ethane gas wasunexpectedly generated and white lumps were formed during the dropwiseaddition, and it could be easily understood that production would bedifficult in cases where the scale of production was increased.Furthermore, an aging reaction was carried out by continuing to stir for3 hours at 25° C., and a large quantity of a precipitated solid wasremoved by being decanted, thereby obtaining a toluene solutioncontaining a triisobutyl aluminum hydrolyzate composition. If it isassumed that both active hydrogens in water reacted with triethylaluminum, thereby generating ethane, and all of the ethane gas wasremoved as gas from the solution, the weight yield was 62%, which wassignificantly lower than in the other synthesis examples.

Example 1-1

100 μl of the toluene solution containing a triisobutyl aluminumhydrolyzate composition obtained in Synthesis Example 1-1 was addeddropwise to a 15 mm-square glass substrate (Eagle XG available fromCorning Incorporated) in an air atmosphere having a temperature of 25°C. and a relative humidity of approximately 40%, spin coated for 20seconds at 4000 rpm using a spin coater, and then heated for 3 minutesat 80° C. to form a thin film.

A thin film such as that shown in FIG. 5 was obtained, and a spectrumsuch as that shown in FIG. 6 was obtained when the thin film wassubjected to IR measurements using an ATR method. A broad Al—O—Alvibration peak was observed in the region of 550 to 1500 cm⁻¹, and itwas confirmed that Al—O—Al bonds were formed. Therefore, it wasconfirmed that an aluminum oxide thin film had been formed. An ATR IRspectrum of the glass substrate itself is shown in FIG. 7, and this isclearly different from FIG. 6.

Example 1-2

A thin film was formed in the same way as in Example 1-1, except thatheating was carried out for 3 minutes at 200° C.

A thin film such as that shown in FIG. 8 was obtained, and a spectrumsuch as that shown in FIG. 9 was obtained when the thin film wassubjected to IR measurements using an ATR method. A broad Al—O—Alvibration peak was observed in the region of 550 to 1500 cm⁻¹, and itwas confirmed that an aluminum oxide thin film had been formed.

Example 1-3

A thin film was formed in the same way as in Example 1-1, except thatthe substrate was a 20 mm-square acrylic substrate (ACRYLITE EXavailable from Mitsubishi Rayon Co., Ltd.), and 150 μl of the solutionwas added dropwise.

A thin film such as that shown in FIG. 10 was obtained, a spectrum suchas that shown in FIG. 11 was obtained when the thin film was subjectedto IR measurements using an ATR method, and it was confirmed that analuminum oxide thin film had been formed. An ATR IR spectrum of theacrylic substrate itself is shown in FIG. 12, and this is clearlydifferent from FIG. 11.

Example 1-4

150 μl of the toluene solution containing a tri-n-octyl aluminumhydrolyzate composition obtained in Synthesis Example 1-4 was addeddropwise to a 15 mm-square glass substrate (Eagle XG available fromCorning Incorporated) in an air atmosphere having a temperature of 25°C. and a relative humidity of approximately 40%, spin coated for 20seconds at 4000 rpm using a spin coater, and then heated for 3 minutesat 80° C. to form a thin film.

A thin film such as that shown in FIG. 13 was obtained, a spectrum suchas that shown in FIG. 14 was obtained when the thin film was subjectedto IR measurements using an ATR method, and it was confirmed that analuminum oxide thin film had been formed.

Example 1-5

A thin film was formed in the same way as in Example 1-4, except thatthe substrate was a 20 mm-square acrylic resin substrate (ACRYLITE EXavailable from Mitsubishi Rayon Co., Ltd.), and 180 μl of the solutionwas added dropwise.

A thin film such as that shown in FIG. 15 was obtained, a spectrum suchas that shown in FIG. 16 was obtained when the thin film was subjectedto IR measurements using an ATR method, and it was confirmed that analuminum oxide thin film had been formed.

Example 1-6

180 μI of the decane solution containing a triisobutyl aluminumhydrolyzate composition obtained in Synthesis Example 1-5 was addeddropwise to a 20 mm-square acrylic resin substrate (ACRYLITE EXavailable from Mitsubishi Rayon Co., Ltd.) in an air atmosphere having atemperature of 25° C. and a relative humidity of approximately 40%, spincoated for 20 seconds at 4000 rpm using a spin coater, and then heatedfor 3 minutes at 80° C. to form a thin film.

A thin film such as that shown in FIG. 17 was obtained, a spectrum suchas that shown in FIG. 18 was obtained when the thin film was subjectedto IR measurements using an ATR method, and it was confirmed that analuminum oxide thin film had been formed.

Comparative Example 1-1

A thin film was formed in the same way as in Example 1-3, except thatthe solution was the THF solution containing a triisobutyl aluminumhydrolyzate composition obtained in Reference Synthesis Example 1-1.

Dissolution of the substrate was observed in that part of the substratethat was in contact with the solution and warping of the substrate alsooccurred. It can easily be understood that industrial applicationsinvolving use of larger quantities of the solution would be difficult,and it is clear that this cannot be used on thinner substrates such asfilms.

(Second Aspect of Present Invention)

Preparation of the solution containing an alkyl zinc partial hydrolyzateand of the solution containing an alkyl aluminum partial hydrolyzate inthe present invention were carried out in a nitrogen gas atmosphere,with all solvents being dehydrated and degassed.

<Number of Moles of Trialkyl Aluminum>

The number of moles of trialkyl aluminum was calculated using thefollowing formula.

[Number  of  moles  of  trialkyl  aluminum] = [mass  (g)  of  trialkyl  aluminum  introduced]/[molecular  weight  of  trialkyl  aluminum  (114.17  in  the  case  of  triethyl  aluminum)]

<Measurement of Physical Properties>

The polypropylene nanocomposite containing zinc oxide and polypropylenenanocomposite containing aluminum oxide of the present invention weresubjected to transmission IR measurements using a FT-IRspectrophotometer (“FT/IR-6100” available from JASCO Corporation).

The polypropylene nanocomposite containing zinc oxide of the presentinvention was subjected to powder X-Ray diffraction (hereinafterabbreviated to XRD) measurements using a powder X-Ray diffractionapparatus (“SmartLab” available from Rigaku Corporation).

The polypropylene nanocomposite containing zinc oxide and polypropylenenanocomposite containing aluminum oxide of the present invention werecut to approximately 100 nm using a microtome equipped with a diamondknife and then subjected to TEM measurements using a transmissionelectron microscope (“H-7100” available from Hitachi, Ltd.).

Synthesis Example 2-1

8.98 g of diethyl zinc (available from Tosoh Finechem Corporation) wasadded to 45.0 g of toluene at 20° C. and thoroughly stirred. Next, theobtained mixture was cooled to −15° C., and 7.857 g of a tetrahydrofuran(hereinafter referred to as THF) solution containing 10 wt % of water([water]/[diethyl zinc]=0.6 (molar ratio)) was added dropwise at −15° C.over a period of 60 minutes using a syringe. After increasing thetemperature to 25° C., an aging reaction was carried out by continuingto stir for 3 hours at 25° C., and a small quantity of a precipitatedsolid was removed by being decanted, thereby obtaining a toluenesolution containing an ethyl zinc partial hydrolyzate.

Synthesis Example 2-2

21.61 g of triethyl aluminum was added to 45.00 g of toluene at 20° C.and thoroughly stirred. Next, the obtained mixture was cooled to −15°C., and 11.09 g of a THF solution containing 10 wt % of water([water]/[triethyl aluminum]=1.0 (molar ratio)) was added dropwise at−15° C. over a period of 60 minutes using a syringe. After increasingthe temperature to 25° C., an aging reaction was carried out bycontinuing to stir for 3 hours at 25° C., and a small quantity of aprecipitated solid was removed by being decanted, thereby obtaining atoluene solution containing an ethyl aluminum partial hydrolyzate.

Example 2-1

Propylene was polymerized using a Ziegler-Natta catalyst(TiCl₄/MgCl₂/dibutyl phthalate type). The obtained propylene homopolymerhad a density of 0.9 g/cm³ and a weight average molecular weight of2.6×10⁵.

30 g of the propylene homopolymer was mixed with 0.3 g (corresponding to1.0 wt %) of an antioxidant (ADK STAB AO-50 available from ADEKACorporation). After thoroughly stirring the mixture, 15.79 g of thetoluene solution containing an ethyl zinc partial hydrolyzate ofSynthesis Example 1 (calculated from [conversion concentration of zincoxide in the solution containing an alkyl zinc partial hydrolyzate (10wt %)]/100×[weight of alkyl zinc partial hydrolyzate]=[total quantity ofnanocomposite (weight of polypropylene (30 g)+weight of converted zincoxide (10 wt % of weight of alkyl zinc partialhydrolyzate))]×[concentration of zinc oxide in nanocomposite (5 wt %)]/100) was introduced and thoroughly stirred. By stirring the thus formedmixture for 12 hours at 50° C. in a nitrogen atmosphere, the propylenehomopolymer powder was impregnated with the toluene solution containingan ethyl zinc partial hydrolyzate.

The solvent was removed by vacuum drying the impregnated propylenehomopolymer powder for 6 hours.

The propylene homopolymer powder, from which the solvent had beenremoved, was melted and heated for 15 minutes at 100 rpm in a mixer at180° C., thereby producing a polypropylene nanocomposite containing zincoxide. Next, the nanocomposite, which had been heated and melted for 6minutes at 230° C., was pressed using a sheet molding machine, and thenquenched, thereby forming a sheet.

A spectrum such as that shown in FIG. 19 was obtained when the sheet wassubjected to IR measurements. In the region of 3900 cm⁻¹, the topspectrum is a spectrum of a propylene homopolymer powder only, and thesecond spectrum is a spectrum of Example 2-1. A broad Zn—O—Zn vibrationpeak was observed in the region of 400 to 800 cm⁻¹, and it was confirmedthat zinc oxide particles had been formed.

A TEM image such as that shown in FIG. 20 was obtained when the sheetwas subjected to TEM measurements. The presence of zinc oxide could beconfirmed. The average particle diameter was calculated from theparticle diameters of 20 average particles in the image, and found to be39 nm.

A spectrum such as that shown in FIG. 21 was obtained when the sheet wassubjected to XRD measurements. The upper spectrum is for Example 2-1,and the lower spectrum is for the propylene homopolymer powder only.Zinc oxide diffraction peaks could be observed.

Example 2-2

A polypropylene nanocomposite containing zinc oxide was formed in thesame way as in Example 2-1, except that a moisture supply step in whicha reaction with water vapor was carried out for 24 hours at 80° C. wasintroduced between the solvent removal step and the melting and heatingstep, and a sheet was then formed in the same way as in Example 2-1.

A spectrum such as that shown in FIG. 22 was obtained when the sheet wassubjected to IR measurements. In the region of 3900 cm⁻¹, the topspectrum is a spectrum of a propylene homopolymer powder only, and thesecond spectrum is a spectrum of Example 2-2. A broad Zn—O—Zn vibrationpeak was observed in the region of 400 to 800 cm⁻¹, and it was confirmedthat zinc oxide particles had been formed.

A TEM image such as that shown in FIG. 23 was obtained when the sheetwas subjected to TEM measurements. The presence of zinc oxide could beconfirmed. The average particle diameter was calculated from theparticle diameters of 20 average particles in the image, and found to be43 nm.

A spectrum such as that shown in FIG. 24 was obtained when the sheet wassubjected to XRD measurements. Zinc oxide diffraction peaks could beobserved. The diffraction peaks were sharper than those for Example 2-1,in which a moisture supply step was not included, showing that thecrystallinity of the zinc oxide had improved.

Example 2-3

A polypropylene nanocomposite containing aluminum oxide was formed inthe same way as in Example 2-1, except that the toluene solutioncontaining an ethyl zinc partial hydrolyzate of Synthesis Example 2-1was replaced with the toluene solution containing an ethyl aluminumpartial hydrolyzate of Synthesis Example 2-2.

A spectrum such as that shown in FIG. 25 was obtained when the sheet wassubjected to IR measurements. In the region of 3600 cm⁻¹, the topspectrum is a spectrum of a propylene homopolymer powder only, and thesecond spectrum is a spectrum of Example 2-3. A broad Al—O—Al vibrationpeak was observed in the region of 400 to 1000 cm⁻¹, and it wasconfirmed that aluminum oxide thin particles had been formed.

A TEM image such as that shown in FIG. 26 was obtained when the sheetwas subjected to TEM measurements. The presence of aluminum oxide couldbe confirmed. The average particle diameter was calculated from theparticle diameters of 20 average particles in the image, and found to be72 nm.

Example 2-4

A polypropylene nanocomposite containing aluminum oxide was formed inthe same way as in Example 2-2, except that the 15.79 g of the toluenesolution containing an ethyl zinc partial hydrolyzate of SynthesisExample 2-1 was replaced with 15.79 g of the toluene solution containingan ethyl aluminum partial hydrolyzate of Synthesis Example 2-2(calculated from [conversion concentration of zinc oxide in the solutioncontaining an alkyl zinc partial hydrolyzate (10 wt %)]/100×[weight ofalkyl zinc partial hydrolyzate]=[total quantity of nanocomposite (weightof polypropylene (30 g)+weight of converted zinc oxide (10 wt % ofweight of alkyl zinc partial hydrolyzate))]×[concentration of zinc oxidein nanocomposite (5 wt %)]/100), and a sheet was then formed in the sameway as in Example 2-1.

A spectrum such as that shown in FIG. 27 was obtained when the sheet wassubjected to IR measurements. In the region of 3900 cm⁻¹, the topspectrum is a spectrum of a propylene homopolymer powder only, and thebottom spectrum is a spectrum of Example 2-4. Broad Al—OH vibrationpeaks were observed in the region of 1600 cm⁻' and at 3000 to 3700 cm⁻¹,and it was confirmed that aluminum hydroxide particles had been formed.

A TEM image such as that shown in FIG. 28 was obtained when the sheetwas subjected to TEM measurements. The presence of aluminum hydroxidecould be confirmed. The average particle diameter was calculated fromthe particle diameters of 20 average particles in the image, and foundto be 75 nm.

INDUSTRIAL APPLICABILITY

The aluminum oxide of the first aspect of the present invention can beused to impart heat-dissipating properties, heat resistance, barrierproperties against air and moisture, an anti-reflection effect, ananti-static effect, an anti-fogging effect or abrasion resistance, as aresin filler for imparting thermal conductivity, as a filler foradjusting the refractive index, reflectance, workability, flexibilityand the like of a resin, as a sintering raw material for fine ceramics,and the like.

The polyolefin-based nanocomposite of the second aspect of the presentinvention can be used as a replacement product for materials of existingproducts that require stability, abrasion resistance, increasedrefractive index, stability against ultraviolet radiation, electricalconductivity ultraviolet radiation absorption or antibacterialproperties, or as a replacement product for materials of products thatrequire adjustment of thermal conductivity, abrasion resistance orrefractive index.

1.-40. (canceled)
 41. A method for producing a composition for forming aparticulate or thin film-shaped aluminum oxide, which is comprised of asolution containing an alkyl aluminum partial hydrolyzate, the methodcomprising: adding water to a solution containing an alkyl aluminumcompound and a non-polar organic solvent at a molar ratio of 0.5 to 1.4relative to aluminum in the alkyl aluminum compound to produce thesolution containing the alkyl aluminum partial hydrolyzate, wherein thealkyl aluminum compound is comprised of a trialkyl aluminum or a mixturethereof, wherein the alkyl groups may be the same or different and have4 to 12 carbon atoms.
 42. The production method according to claim 41,wherein the trialkyl aluminum is an alkyl aluminum compound representedby general formula (1) below:AlR¹ ₃   (1) in the formula, le represents an isobutyl group, an n-hexylgroup or an n-octyl group, and the three R¹ groups may be the same ordifferent.
 43. A composition for forming a particulate or thinfilm-shaped aluminum oxide, which is comprised of a solution containingan alkyl aluminum partial hydrolyzate and a non-polar organic solvent,wherein the alkyl groups in the alkyl aluminum partial hydrolyzate maybe the same or different and have 4 to 12 carbon atoms, the molar ratioof alkyl groups relative to aluminum atoms falls within the range of 0.2to 2, and the molar ratio of oxygen atoms relative to aluminum atomsfalls within the range of 1.4 to 0.5.
 44. The composition according toclaim 43, wherein the alkyl groups are at least one alkyl group selectedfrom the group consisting of isobutyl groups, n-hexyl groups and n-octylgroups.
 45. A method for producing an aluminum oxide thin film, themethod comprising: coating a substrate with the composition according toclaim 43, and then removing the non-polar organic solvent to form analuminum oxide thin film.
 46. A method for producing a particulatealuminum oxide-containing substrate, the method comprising: mixing thecomposition according to claim 43 with a substrate-forming binder, andthen removing the non-polar organic solvent to form a particulatealuminum oxide in the binder.